 /*******************************************************************************
  * Copyright (c) 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  ******************************************************************************/

 package org.eclipse.core.commands;

 /**
  * <p>
  * A listener to the execution of commands. This listener will be notified if a
  * command is about to execute, and when that execution completes. It is not
  * possible for the listener to prevent the execution, only to respond to it in
  * some way.
  * </p>
  *
  * @since 3.1
  */
 public interface IExecutionListener {

     /**
      * Notifies the listener that an attempt was made to execute a command with
      * no handler.
      *
      * @param commandId
      * The identifier of command that is not handled; never
      * <code>null</code>
      * @param exception
      * The exception that occurred; never <code>null</code>.
      */
     public void notHandled(String commandId, NotHandledException exception);

     /**
      * Notifies the listener that a command has failed to complete execution.
      *
      * @param commandId
      * The identifier of the command that has executed; never
      * <code>null</code>.
      * @param exception
      * The exception that occurred; never <code>null</code>.
      */
     public void postExecuteFailure(String commandId,
             ExecutionException exception);

     /**
      * Notifies the listener that a command has completed execution
      * successfully.
      *
      * @param commandId
      * The identifier of the command that has executed; never
      * <code>null</code>.
      * @param returnValue
      * The return value from the command; may be <code>null</code>.
      */
     public void postExecuteSuccess(String commandId, Object returnValue);

     /**
      * Notifies the listener that a command is about to execute.
      *
      * @param commandId
      * The identifier of the command that is about to execute, never
      * <code>null</code>.
      * @param event
      * The event that will be passed to the <code>execute</code>
      * method; never <code>null</code>.
      */
     public void preExecute(String commandId, ExecutionEvent event);
 }

